1. Field of the Invention
The present invention relates generally to pulse processors and, more particularly, to a pulse processor for use in scintillation counters.
2. The Prior Art
Scintillation counters find important and widespread applications in oil well data logging and in scintillation cameras used in the relatively recent but fast-growing field of nuclear medicine. In oil well data logging, the resultant analog signals normally have to be transported over long distances in noisy environments. Consequently, the signals are subjected to considerable distortions and, on occasions the signals are lost altogether. In scintillation cameras, on the other hand, when counting at high levels, the zero reference D.C. voltage level is also raised to a high level. As a result, it becomes progressively more difficult to measure the heights of the analog signals, affecting thus the accuracy of the readings. Further, scintillation cameras usually have a plurality of channels of pulse collectors. For reasons of accuracy, noise susceptibility, count rate or simplicity, it is often advisable to process the signals of only some of the channels and to disregard the signals from the other channels. Achieving such selective processing of the signals by multiplexing or by switching the analog signals is at best a slow and cumbersome process. There has existed, therefore, a need to process signals in scintillation counting in a manner that avoids the above disadvantages.